Process for electrolytic preparation of vanadium oxide



g- 5, 1952 M. J. PORTANOVA ET AL 4 PROCESS FOR ELECTROLYTIC PREPARATIONOF VANADIUM OXIDE Filed Nov. 2, 1948 INVENTORS M01710 J PortanovaATTORNEY Patented Aug. 5, 1952 ritoonss FOR; ELECTROLYTIC PREPABZA-.'TlQNOF VANADIUM OXIDE MarioJrPoItanova; Brooklyn, Y., and Arthur 7Rcsinger, Belleville, N. J assignors to Natural Products Refining 00.,Jersey City, N. J.,

c rpo ation ofDelaware p a 2, 1943; Serial 'No. 57,864 1 4 Claims.(01.204-96) Application November :Qerinvent :Ielat s, t t eprq e s .-:pep win ana nd QY zOebY t lectro of Sodium te; N Voai so u nsran zthe aaeara us dther e act re wh sknad mae ida v Jand another object is toprovide ian electrolytic .9 o na lins..ih .:pr bec o all-effective n medcalswaman. areno-m i ana e In the practice of this inventionathesodiumvxanadet sol t o u ectro1 s ;m y be "remaine an d re l' Q Fprie i -u rsaidvanadate solution maybe produced by leachtv beie v t a e y at n rusmeun x wi ir r sind t u n ane iu :.heari -;m wis e 1 it o mor alk li.met ompou s such; prizi rm se ised menene Q. 1 m- Y.d9X,-. 1 qtets umcarb nat .-..imjt .u m.- erea s v mi tur I desirem proportions. Another.v a an btain n t sQ um-Y n da e solut o imayib d e e 1 1 :a kv ieqiumrb nemater al o re Linen goxidized state -in aqueous-.; solutionsof alkaliim wqo i o ed Such a so umhy o da s fiii mk ar n t ,.pq a iim-i y ox ei potas ium wear-bonate or mixtures, thereof, in any-desiredproportions. These methods ofobtaining thesoor otheu alkali-vmetalfvanadate; solutions l i ieat s b l Puws a i-wmi -v-snre- ,.Ivi ously,well lrnown. v Forrexamplea-vre can pre- ,pare a sodium vanadatesolution firom a vanav. di1'i rn -.b eairing ,material such as: acrudeise dium .polyvanadate; obtained as, a i y-product ni vansdissolved; in caustic soda solution 1 or mother ia k t m qu s. 7 oltionfi e t e ment of at crude sodium polyvanadate ore; other impurevanadium bearing material ;-in the 1 ox- Qidized state has ,the.advantage -that;- ;any mpurities -insoluble in; alkaline solutions an hesp e-te imm he lu le; s di m anedet r a-filtration or settling before'elec rolysis.

' The Y crude sodium-polyvanadate referred to may. for instance; kee-that tvhicl' is obtained; as V a r d v l t w en of ani1-im 19 mranium:ores for instance by roasting; uranium I -w tai va a i o o n s a an-purit-y withan alkali-metal compound such for examp as q u na e-sthydroxide iz potassium carbonate, potassium hydroxide or xnixturesthereof in any desired. proportions; yto produce an' alkali uraniumcompound and then 1 treating the; product thus obtained withsulturicacid ot any, desired strength, out for instanc s thereof 1 in any usindufstriesfflfhis impure sodium .polyvanadate sulfuric acid containing23% by Weight of vv'ater, --to precipitate out the crude sodiumpolyvanadate. The sodium polyvanadate is usually a mixture of-variab1eproportions 'ofithe following acids, wp artly dehydrated; with'thesodium salts thereiof: 1

Orthovanadic acid, OV(OH)3 'Metavanadic acid VQzKOH) and ofttimes, also;oneforboth of'jthe .following acids, partly dehydrated, 'withfthefsodiumsalts thereof Pyrovanadic acid vorori) 2,0310; (em

Tetravanadic v acid, Y

, vororn z.oyoonovoorrovorom 2 Previous electrolyticmethods of treatingthe sodium vanadate solutions to produce vanadium oxide resulted inobtaining a vanadium? oxide containing considerable" amounts of sodiumjjcomwpounds and other impurities-such as linie and J silica; and;furthermore, the {use} of anodes" of p1a'tinum,1 whi'ch has previouslybeen saidto, be theionly metal that-Will 'resist the electrolyticoxidation at tha anode-has 'made the previous methods impractical andtoo expensive.

An object of our invention, thereforegis'to provide an electrolytic'cellby means of' which the process above referred to c'anbe efiec ti velyaccomplished and in which anodes and-cathodes of an: effective"character, made of-readily available materials-areutilized, andinwhich, by means of a rotating anode the vanadium-oxide may beefiectively removed continuously in the -process 1byscraping theprecipitated vanadium oxide therefrom. Another object is to control theY concentrations, temperatures} and current densities in the process'toenable theseadvan- 'tageous objects tobeattained;

' paratus- \While our invention is capable of being carried out in manydifferent-ways and withmany difierent' types of. apparatus, by' wayofexample we have shown only. one embodiment'of -the apintheaccompanying drawings, in

which I Fig; l is .-a vertical'section of an electrolytic cell usedinvaccordance'with our invention; and

Fig. 2 is a plan view of 'thesame.

--The present process; by employing theH pe of apparatus hereinafterdescribed together with the conditions of properconcentrationand-subsequent repulping'of the vanadium oxide, resultsinthe manufacture of a high gradeproductcontaining evenas much as 97-%--vanadium-oxide,

thezremainingg.-3 being substantially-comprised nim? l ably'hdju'sted toa .pH of 7.0 133 using; a slight caustic soda solution haying a,-1%-strengti l foninstance. 4 l

a v The;two-compartment;;electrolytic ce1l-is,;for

. bxampl'e, provided with-anv outer hollow cylindri- 'cal corrosiveelectrolytic attibn at the anode owing" .10v bf iron The making "ofxthejanode of f to the formation 6f a protective vfilm ,of oxide rying astationary brush l9 which is connected by a wire 20 to the source ofelectric current to which the wire also leads. The said shaft I8 hassecurely fastened thereto a bearing member 2| having beneath the same aball race 22 to re= =ceive, balls 23 supported a stationary ball race24, to act'as a thrust'bearing for supporting the steel "or iiibil, orof iron alloys containing carbon and silicon, such as cast'irori,'etc.,--mak'es this" lprebess especially practical and feasible for themanufacture of vanadium oxide commercially;

In fact, by this means any water soluble alkali metal vanadium com oundmaybe eifectively electrolyzed to t'aiod'llfie the vanadium oxide by ourprocess,

As an example in carrying but the proces and means which may be utilizedin'c'ai'rying out this inventionetne erucesodium' or potassium fpo1y=vanadate aybe converted to a soluble sodium or ther alkali-metal withaba'ustic' soda-solution or other alkali-metal vana'd'ate by digestingit compound in aqueous solution; The said caustic soda, solution orother alkalhmetal compound aqueous solution c ntain an desired oer=centage erwater, but for instancefrorn 7,, to Weight otwater. Thesolution is prefer excess of alkali polyvanadate; The isert-mermpurities are then filtered off. The filtrate is then of .96 ea;of vanadium setto a concentration v oxide peer to. this gr}. Navo's' herto.) This se= lutioh is'new run into 'the anode chamber of a twocompartment cell, constructed as hereinafter described, Thecathodechamber is filled with a steel vessel-t having anannularchamber 2therein. forming a jacket for the introduction .of any desired heatingmedium, as for example steam, which may be supplied thereto bymeans of apipe 3 havinganinlet 4 connected to the bottom of the cylindrical vesselI, and'which may alsoserve as a means for drawingyofi any condensedwater therefrom. The chamber 2 has -an inner cylinder 5 conne ted to afiat annular bottom'portio'n B providedwith-a conical lower centralportion 1, whichleads to a draw-off pipe .8 havingavvalve'9'communicating with an outletpipe ID. A porous porcelain cylindricaldiaphragm is set into. the bottom of'the cylinder .5 man annularconcrete'layer l2, and a conical continuation-of the said porcelaincylinder I l'extends downwardly over the conical steel bottom 1 and intothe draw-off pipe 8 up to the position ofthe valve 9.Thisporous'porcelain' diaphragm cylinder II has, provided on the outsidethereof, a cathode chamber I3:in which there is a per- 4 foratedcylindrical steel sheet mywhich may,

instead, however, be of copper, carbon or'lvionel' ,metal, to serve as acathode,which is connected to an electrical conduit orwire lS. Withinthe porous diaphragm, cylinder H there is' also formed an anode chamberlfiqhaving therein a rotating solid cylindrical steel or iron anodel7.

The anode l1 may be made of some other metal, for instance platinum, butnot so advantageously.

,;The anode IJ'may-be carried on a shaft ls wh'ich is rotated by ,meansof .any suitable source-of power andha a conducting cylinder thereoncarwhich is preferably weak,

shaft I8, by being carried within an insulating .fibre clamping block 25secured by screws 26 to a yoke 21, the lower downwardly directed iids ofwhich are fiancee and fastened by screws it! to flanges '29 located nthe top or a h rizontal annular cover plate 30 which connects thewalls I"and 5, forming the chamber 2 located between the same. The porcelaincylindrical diaphragm l i; furthermore, has on its inner face twovertical flan es 3| and 32 provided with vertical slots 33 and 311,respectively, for receiving therein scrapers 35 and 36, made of anydesired insulating inert flexible or plastic material so that the inneredges thereof the against the rotatin steel anoee Ii to removethevanadium oxide, which fofnls taere n dur ng the lect'i olysis.

"vanadate obtained as above and having the there is also a draweoff pipe38 having a valve j ably, a solution of 1% by Weight of sodium hydroxidein water, by means of the pipe 31. The anode chamber'fli is then filled,by means of the pipe M, with the sodium vanadate solution, that is to"say containing the crude sodium poly= strength above referred to, asfor instance a corl= (.oiegr. NaVOo per cc.).

centration of; ".03 gr. of vanadium oxide per cc. 7 The temperature isthen raised to about 60 to 90 (3., but preferably 90", by means of thesteam and then maintained in this range. The anode I7 is rotated at anydesired speed, but for example at about 1 R. P. M!

Direct current is then applied to the electrodes,

which point the "take. place."

said' current being of any desired character, but for example of 25 to35 amperes per square foot of anode surface at 6 to S'volts.Thevafnadium oxide, V205, is thus formed on the outer surface of theanode l I! and this'is continually being removed by the scrapers 35, 36as the anode is rotated, in a loose granular form so that it falls tothe bottom and is easily removed through the valve 9, after which it canbe filtered and repulped by suspending it in water and washing it in anydesired manner. The end of the electrolysis is shown by a sudden drop ofamperage, atw'hich time the anolyte in'the chamber I 6 containing thesuspended vanadium oxide is drawn off for'further'proces'sing, as abovereferred to. The cell I6 can then again be filled with fresh sodiumvanadate solution and the electrolysis repeated. The electrolysis ofeach batch is preferably" continued, in the manner above described,until about of the vanadium present is' precipitated as vanadium oxide,at sudden drop in' amperage will Preferably, also, the precipitatedvanadium oxide is filtered to separate it from the'mother liquor;Thereafter, 'it is then suspended in Water, as above referred to, inany.- desired proportion, which may be, for instance, about gr. ofvanadium oxide per 100 cc. of water, and stirred at a temperature ofabout 90 to 100 C. for at least /4 of an hour. If the vanadium oxide isprecipitated from a sodium vanadate solution containing the equivalentof .06 gr. vanadium oxide per cc. of the solution or less, and if thevanadium oxide produced is repulped under the conditions describedabove, the resulting dry vanadium oxide will have a purity of about 97%V205, and will contain a minimum amount of sodium salts. The motherliquor containing the unprecipitated vanadium oxide and other solublesalts, such as sodium uranate, may be concentrated, cooled and treatedto recover vanadium oxide. The solution may then be filtered and thevanadium oxide added to a fresh batch of vanadium bearing material inthe oxidized state. This mixture is then dissolved in caustic sodasolution to form soluble sodium vanadate, as previously described forthe preparation of the anolyte.

It will be understood that in conducting the process, as the vanadiumoxide forms at the anode the cathode liquor will increase in alkalinity.If desired, the catholyte in the chamber I3 can be drawn ofi after eachbatch removal of the vanadium oxide, or can be continuously removed byrunning water into the chamber H3 at a slow rate from any suitablesource of fresh water supply and allowing the caustic soda solutionwhich has been formed during the electrolysis, to overflow by means ofthe discharge pipe 42.

The caustic soda which is produced at the oathode can, furthermore, beused to dissolve a fresh batch of the oxidized vanadium-bearingmaterial, as for instance the uranium ore containing vanadium, abovereferred to. In this way, the caustic soda necessary for the solution ofthe vanadium-bearing material can be used over again repeatedly in theprocess.

If desired, the vanadium oxide precipitated and repulped as above, canbe rendered anhydrous by drying, at a temperature of 300 C., forexample.

While we have described our invention above in detail we Wish it to beunderstood that many changes may be made therein without departing fromthe spirit of the same.

We claim:

1. An electrolytic process for obtaining vanadium oxide, comprisingsubjecting an alkalirr tal vanadate water solution to electrolyticaction with the aid of a steel anode so as to obtain a precipitate ofvanadium oxide substantially free from iron, at a concentration adjustedto approximately .078 gram of sodium vanadate per cc. at a pH of 7 .0and a cathode in acatholyte of a weak caustic soda solution, with adirect current density of approximately 25 to 35 amperes per square footof the anode at 6 to 8 volts and a temperature of about 60-90 C.

2. An electrolytic process for obtaining vanadium oxide, comprisingsubjecting an alkalimetal vanadate water solution to electrolytic actionwith the aid of a steel anode so as to obtain a precipitate of vanadiumoxide substantially free from iron, at a concentration adjusted toapproximately .078 gram of sodium vanadate per cc. at a pH of 7.0 and acathode in a catholyte of a Weak caustic soda solution,,with a directcurrent density of approximately 25 to 35 amperes per square foot of theanode of 6 to 8 volts and a temperature of about -90 C., filtering oilthe precipitated vanadium oxide from the anode liquor, repulping thevanadium oxide with water at a temperature of 90-100 C. for at least ofan hour and then filtering and drying the purified vanadium oxide.

3. An electrolytic process for obtaining vanadium oxide, comprisingsubjecting an alkalimetal vanadate Water solution to electrolytic actionwith the aid of a steel anode so as to obtain a precipitate of vanadiumoxide substantially free from iron at a concentration adjusted toapproximately .078 gram of sodium vanadate per cc. at a pH of 7.0 and acathode in a catholyte of a weak caustic soda solution, with a directcurrent density of approximately 25 to 35 amperes per square foot of theanode at 6 to 8 volts and a temperature of about 60-90 C., theelectrolysis being continued until about 75% of the vanadium present ispreciditated as vanadium oxide when a sudden drop in amperage takesplace.

4. An electrolytic process for obtaining vanadium oxide, comprisingsubjecting an alkalimetal vanadate water solution to electrolytic actionwith the aid of a steel anode so as to obtain a precipitate of vanadiumoxide substantially free from iron, at a concentration adjusted toapproximately .078 gram of sodium vanadate per cc. at a pH of 7.0 and acathode in a catholyte of a weak caustic soda solution, with a directcurrent density of approximately 25 to 35 amperes per square foot of theanode at 6 to 8 volts and a temperature of about 60-90 C., theelectrolysis being continued until about 75 of the vanadium present isprecipitated as vanadium oxide when a sudden drop in amperage takesplace, filtering off the precipitated vanadium oxide from the anodeliquor, repulping the vanadium oxide with water at a temperature of90-100 C. for at least of an hour and then filtering and drying thepurified vanadium oxide.

MARIO J. PORTANOVA. ARTHUR ROSINGER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,050,796 Bleecker Jan. 21, 19131,322,000 Ellis Nov. 18, 1919 1,435,886 Acton et al Nov. 14, 19221,719,984 Klein et a1. July 9, 1929 1,807,585 Becker June 2, 19312,448,848 Van Loenen Sept. 7, 1948 OTHER REFERENCES

1. AN ELECTROLYTIC PROCESS FOR OBTAINING VANADIUM OXIDE COMPRISINGSUBJECTING AN ALKALIMETAL VANADATE WATER SOLUTION TO ELECTROLYTIC ACTIONWITH THA AID OF A STEEL ANODE SO AS TO OBTAIN A PRECIPITATE OF VANADIUMOXIDE SUBSTANTIALLY FREE FROM IRON, AT A CONCENTRATION ADJUSTED TOAPPROXIMATELY 078 GRAM OF SODIUM VANADATE PER CC. AT A PH OF 7.0 AND ACATHODE IN A CATHOLYTE OF A WEAK CAUSTIC SODA SOLUTION, WITH A DIRECTCURRENT DENSITY OF APPROXIMATELY 25 TO 35 AMPERES PER SQUARE FOOT OF THEANODE AT 6 TO 8 VOLTS AND A TEMPERATURE OF ABOUT 60-90* C.